Fig. 5.

The sandfish lizard (Scincus scincus) (a) at rest on the 0.3-mm diameter glass particles. (b) Multiparticle discrete element method (DEM) simulation of the sandfish swimming subsurface in a simulated box of glass particles, 3 mm in diameter. (c) Midline trajectories of the simulated sandfish during swimming. (d) Forward swimming speed versus frequency of undulation in a biological experiment (points), DEM simulation (dashed lines) and resistive force theory (solid lines) in a loosely packed granular medium (58% by volume) (Maladen et al. 2011). (e) Physical robot model of the sandfish at rest on a granular medium of plastic particles, 6 mm in diameter. The robot swims with performance comparable with that of the live organism.